Method of potting instrument assemblies and construction thereof



1958 J. F. CONNELLY ET AL 2,864,057

METHOD OF TTING INSTRUMENT ASSEMBLIES AN ONSTRUCTION THEREOF Filed April 15, 1954 5 Sheetg-Sheet l TIE-.3

F i 5 a Dec. 9, 1958 F. CONNELLY ET J AL 2,864,057 METHOD OF POTTING INSTRUMEN SSEMBLIES AND CONSTRUCTION THE F Filed April 15, 1954 5 Sheets-Sheet 2 Ira-.11

Tana f J v IaZNVENTORS K5 53 6. dfo va 54 BY 0 il RNEY 1958 J. F. CONNELLY ET AL 2,864,057

METHOD OF POTTING INSTRUMENT ASSEMBLIES AND CONSTRUCTION THEREOF Filed April 15, 1954 5 Sheets-Sheet 5 3.13.. E U 315-15 I 112.. El

1958 J. F. CONNELLY ETAL 2,864,057

METHOD OF POTTING INSTRUMENT ASSEMBLIES AND CONSTRUCTION THEREOF Filed April 15, 1954 5 Sheets-Sheet 4 Fz= E E IN VENTORS 50/? 5, 60 @3523 $mm4,9,v

BY Ta I A BY 1958 J. F. CONNELLY ETAL 2,864,057

OTTING ENT EMBLIES METHOD OF P INSTRUM AND CONSTRUCTION THERE Filed April 15, 1954 5 Sheets-Sheet 5 52 5/ xom j 5 ,4 l ra er THE; 5 3 v TTORNEY I United States Paten METHOD OF POTTING INSTRUMENT ASSEM- BLIES AND CONSTRUCTION THEREGF John F. Connelly-andLmn E. Thomas, Era, New Haven, Conn.

ApplicationApril. 15, 1954; Serial No. 423,486 S'Claims. (Cl. 324156) Our invention relates broadly to electrical measuring instruments and more particularly to a method of producing a construction of. potted assembly for electrical measuring instruments- One of the objects of our. invention is to provide a method of producing electrical measuring instruments at relatively low cost on amass production scale in which associated components are molded in assemblies readily connectible with the measuring instruments.

Another object of our invention is to provide a construction of miniaturized electrical measuring instrument in which circuit components such as rectifier assemblies are molded in a unit adapted to be associated with the electrical measuring instrument within the confines of the dimensional limits of the miniaturized meter for compactly associating the circuit components with the meter.

Still another objects of our invention is to provide a construction of potted assembly for the circuit components for an electric meter. by which the. entire assembly may be readily electrically connected with or removed from the meter and replaced by an assembly of the same dimensional contour. on the rear of the meter.

Still another object of our invention is to provide a construction of potted assembly for the circuit components of a miniaturized. electric meter which may be associated. with an illuminatingdevice arranged for rendering conveniently visible the indicating scale of. the miniaturized meter.

Other and'further objects ofv our inventionare to provide a method of producing a potted assembly for the circuit components of miniature electric meters and a construction of such assembly as set forth more fully in the specification hereinafter following by reference to. the accompanying. drawings, in which:

Fig. 1' is a front. elevational, viewof. a panel for a potted circuit component assembly for use withv a miniaturized meter, showing one manner of mounting a pair of resistors;

Fig. 2 is a side elevational' view of the assembly illustrated in Fig. 1.;

Fig. 3 shows a panel arranged to support asingle resistor for association with an electrical measuring instrument;

Fig. 4. is a side elevational view of the assembly shown in Fig. 3;

Fig. 5 is a front elevational' view of. a panel with a rectifier and a resistor assembl'edthereon;

Fig; 6 is a side elevational view of the assembly shown in Fig. 5.;

Fig. 7 is a fragmentary perspective view, of one method of the first step used for molding. the potted instrument assembly in accordance with-our invention;

Fig. 8 shows a succeeding step in the manufacturing process. of the potted instrument assembly;

Fig.- 9 is a perspective View illustrating the completed potted assembly removed from the mold;

Fig. 10 is a perspective view of the first step in another ice Eli

method of preparing the potted. instrument assembly of our invetniong.

Fig. 11 is a perspective view showing the succeeding step in the sequence according to the method illustrated in Fig. 10;

Fig. 12 is a cross sectional view partially in elevation, showing the completed potted instrument assembly produced by either of the molds illustrated in Figs. 7-8 or the molds illustrated in Figs. 10-11;

Fig. 13 isa front viewof the miniaturized meter with which the potted instrument assembly is associated;

Fig. 14 is a, side elevational view of the miniaturized meter shown in Fig. 13 and illustrating the potted instrument assembly associated with the meter and partially broken away and illustrated in section;

Fig. 15 is a rear view of the potted instrument assembly illustrated in position on the miniaturized meter;

Fig. 16 is a schematic wiring diagram of the circuit components. used in the potted instrument assembly depicted in Figs. 3-4;

Fig. 17 schematically shows the circuit components including arectifier as used in the potted instrument assembly depicted in Figs. 5-6;

Fig. 18 schematically illustrated a modified arrangement of the circuit components which may be mounted within the potted instrument assembly;

Fig. 19 illustrates in side elevation a modified arrangement of potted instrument assembly and an illuminating device for electric meters;

Fig. 20 is a front view of the electric meter illustrated in Fig. 19;

Fig. 21- is a rear view of. the electric meter illustrated in. Fig. 19, and particularly illustrating the potted instrument assembly and the illuminating device used with the meter.

Fig. 22 is. a longitudinal sectional view through the meter illustrated in Figs. 20-21;

Fig. 23 is a front elevational view of the panel for mounting the electric circuit components for the form of the meter illustrated-in Figs. 20-22, prior to the potting operation, the View showing the arrangement of a single resistor onthe panel;

Fig. 24 is a. side elevational view trated in Fig-.23;

Fig. 25 is a fragmentary sectional view on line 2525 of Fig. 23, showing the manner of mounting the terminals on the panel;

Fig. 26. is a front elevational view of a panel provided for mounting a single resistor and a rectifier;

Fig. 27 is a side elevational view of the arrangement illustrated in Fig. 26;

Fig. 28 shows in front. elevation an arrangement of a panelfor mounting two resistors;

Fig. 29 is a side view of. the panel shown in Fig. 28;

Fig. 30 is a front elevational view of a panel showing the arrangement of a rectifier and two resistors thereon;

Fig. 31. is aside view of the panel illustrated in Fig. 30;

Fig. 32 is a side elevational view partially broken away and illustrated in section of a fragmentary portion of a meter and a potted assembly including the panels having any one of the arrangements illustrated in Figs. 23-31, the potted assembly being partially broken away and illustrated in section;

Fig. 33 is an end view of the in Fig. 32;

Fig. 34 is a transverse sectional view taken through a modified form of av potted assembly in a plane on either side of the position in which the electrical components mountedon the panel are embedded;

Fig. 35 is a side elevational view of a meter illustrating a further modified arrangement of potted assembly and.

of the panel illuspotted assembly shown illuminating device interposed between the potted assembly and the electrical meter and utilized for illuminating the rear of the meter scale;

Fig. 36 is a vertical sectional view taken substantially on line 36-36 of Fig. 35;

Fig. 37 is an end view of the potted assembly shown in Fig. 35;

Fig. 38 is a bottom plan view of the potted assembly and illuminating device illustrated in Figs. 35-36;

Fig. 39 is a vertical sectional view through the potted assembly and illuminating device of Figs. 35-38; and

Fig. 40 is a vertical sectional view taken in a longitudinal direction through one of the fastening means for mounting the potted assembly and illuminating means with respect to the electric meter.

Our invention is directed to a method of molding circuit components into a compact assembly which may be attachably mounted with respect to an associated electrical instrument. We mount circuit components on a panel member which conforms to the contour of the electrical instrument with which the panel member is to be associated. The panel member with the circuit components mounted thereon is placed in a cavity mold and plastic material flowed therearound for completely embedding all of the circuit components. The plastic molding conforms in contour with the instrument with which the circuit components are to be associated. A variety of moldable materials may be employed and a variety of arrangements of circuit components are possible. Moreover, in addition to the potted assembly of circuit components we may associate with the potted assembly and an electric meter for example, an illuminating device arranged to direct light on the scale of the meter. The illuminating device and the potted assembly both correspond in contour to the electrical instrument with which they are associated which enables the miniature meter or measuring instrument to be compactly mounted with respect to associated equipment on a panel. The several embodiments of our invention shown herein are to be considered in the illustrative sense and not in a limiting sense as a variety of arrangements will suggest themselves in accordance with thedisclosure of the main plan of the invention set forth herein.

Referring to the drawings in detail, a panel 1 of insulation material, of substantially circular contour, is provided as a mounting means for the four terminal members 2, 3, 4, and 5 which project on opposite sides of the panel and serve on the one side as mechanical supports and electrical connections for the resistor, designated at 6 and 7, including metallic leads extending therefrom and connected therewith and with extensions of the terminals which project from the rear of the panel. The panel 1 is symmetrically apertured at 8 and 9 for the passage of the fastening bolts indicated more clearly in Figs. 14, 15 and 34, at 10 and 11.

In Figs. 3 and 4 we have illustrated the manner in which a single resistor 12 may be supported between the projecting ends of terminals 3 and 5 while the terminals 2 and 4 are shunted by a conductor 14.

In Figs. 5 and 6 we have illustrated an assembly in which a rectifier 15 and a resistor 16 are supported on and electrically connected with leads which extend from the projecting ends of the terminals 2, 3, 4 and 5, the several components and their connecting leads being confined within their dimensional limits of the panel 1.

The panel 1 with the associated circuit component thereon is then dropped into a metallic cylindrical mold 116 having a base centrally apertured at 17 through which a plunger 18 carrying a disc 19 thereon may be pushed upwardly. The panel 1 rests against the disc 19 with the circuit components, such as represented at 12, facing upwardly within the cavity formed by the metallic cylindrical mold 16. The inside of the cylindrical cavity mold 16 is now coated with silicon mold. release... Into this cavity the plastic insulation material, for embedding; the electrical circuit components, is poured as represented: in Fig. 8, by the mass 20. This molding materlal may be' a thermo-setting epoxy potting compound or a resin, or

Hysol 6020, or a thermoplastic, self-polymerizing resin (methyl methacrylate type), or other potting compounds. The potted assembly is allowed to harden and then is removed from the mold 16 by movement of plunger 18 upwardly, producing the product illustrated in Fig. 9 in which the molded mass 20 adheres to the panel 1. Apertures S and 9 are drilled out as represented at 8:1 and 9a and counterbored on the meter side of the device as represented at 8b and 9b. We have illustrated an alternate method of molding the potted assembly in Figs. 10 and ll wherein a pattern 21, which simulates the final potted assembly, is positioned centrally within the container 22 and the space 23 around the pattern filled with a flexible mold potting compound such as Geon" made by B. F. Goodrich Co., or Hysol (flexible type) 6020 made by Houghton Laboratories, as represented at 24 in Fig. 11. This molding compound is allowed to set approximately four hours at room temperature until it reaches a rubbery consistency. The pattern 21 is then withdrawn, leaving the cylindrical cavity 25. The panel with the electrical components mounted thereon is now dropped into the cavity mold with the electrical components, designated at 12, directed upwardly. The cavity 25 is now filled with the potting compound or resin embedding the circuit components 12 which extend upwardly from the panel 1. This compound is allowed to harden and attain dimensional stability. We may allow the compound to harden under vacuum for removing bubbles to give a homogeneous mass. The molded body provides an end product similar to that illustrated previously in Fig. 9 and now shown in Fig. 12 in which the molded material 20 embeds the circuit components 12 supported on the projecting ends of terminals 3 and 4 from panel 1 where the surface of panel 1 is adhesively united with the molded body 20. The molded body 20 is now drilled and countersunk as heretofore explained in connection with Fig. 9. The potted assembly thus produced is applied to an electric meter as illustrated in Figs. 13, 14, and 15, the meter being of miniature type having an indicating scale, represented at 26 over which movable indicator 27 operates as shown in Fig. 13. The meter is provided with a screw-threaded body portion illustrated in Fig. 14 at 28 which is engaged by adjustable ring 29 for gripping the meter within an apertured panel in coaction' with flange 30. The rearwardly projecting terminals on the meter housing are represented at 31 and 32 which include screw-threaded ends 31a and 32a. The potted assembly 20, longitudinally apertured at Sat and 9a, is fastened to the screw-threaded ends 31a and 32a of the terminals of the meter by the internally screw threaded fastening means 10 and 11, having headed ends 1011 and 11a and provided with connecting lugs 10b and 11b, shown more clearly in Fig. 34.

In Fig. 16 we have diagrammatically shown an electrical circuit arrangement for the electrical components 12 and 14 mounted on panel 1, shown in Figs. 3 and 4. In Fig. 17 we have shown diagrammatically the electrical circuit components for the assembly illustrated in Figs. 5 and 6, including the resistor 7 and the full wave rectifier 15 connected between the terminals carried by panel 1.

In Fig. 18 we have diagrammatically shown a modified arrangement of electrical circuit in which the circuit components, as described in connection with Fig. 17, are mounted onpanel 1 and in addition thereto there is included a shunt resistance 33.

In Figs. l9-32 we have shown an application of the method and structure of our invention to a miniaturized electric meter which also includes means for illuminating the scale of the meter. In this arrangement the miniature electric meter is represented generally at 34 having a visible scale over which indicator 36 operates. The scale 35 is formed on a translucent plate as represented more clearly in Fig. 22 through which light rays in a beam designated at 37 may be focussed through a lens 38 on the rear of the translucent scale 35 visible through the front transparent plate 39 of the electric meter. The rear of the electric meter carries terminals 41 and 42 thereon, forming attachment means for the potted assembly illustrated at 43. The potted assembly 43 differs from the potted assembly 20 as heretofore explained, in that potted assembly 43 is approximately semi-cylindrical in contour, leaving sufficient space for the attachment of an illuminating device, represented at 44 to the rear of the housing of the electric meter. The illuminating device 44 is detachably secured to the rear of the meter housing by screw means indicated at 45 and 46. The illuminating device includes an incandescent lamp designated at 47 which is resiliently retained in position by spring means 48 and electrical circuit connections completed thereto through terminal lugs 49. The light beam from incandescent lamp 47 is projected through lens 48 which focuses the beam 47 on the rear of scale 35. The potted assembly 43 is provided with terminals 41a and 42a thereon which connect with the terminals 41 and 42 of the electric meter. Terminals 50 and 51 are embedded in the potted assembly 43 for establishing connection with the circuit components which are surrounded by the insulation material forming the potted assembly.

In Figs. 22-24 we have illustrated one arrangement of the potted assembly for the meter illustrated in. Figs. 20-21, in which the panel of insulation material, designated at 52, supports the terminals 50 and 51 which are embedded therein and in co-action with the fastening screws which we have indicated generally at 53 and 54 and serve as a mounting and electrical connecting means for the circuit components within the potted assembly. In the example illustrated in Figs. 23 and 24, a single resistor 55 is provided but it will be understood that other electrical arrangements may be provided as illustrated in Figs. 26-31.

In Figs. 26 and 27 I have shown panel 52 serving as a mount for the rectifier 56 and the electrical resistor 55.

In Figs. 28 and 29 I have shown the panel 52 serving as a mount for two resistors 55 and 57 electrically connected with the terminal lugs 58 and 59 leading to the fastening and electrical connecting screws 53 and 54.

In Figs. 30 and 31 I have shown an arrangement of rectifier 56 with a pair of resistors such as 55 and 57 electrically connected as shown with the terminal lugs 58 and 59. The assembly on the panel 52 is subjected to either of the molding processes set forth in Figs. 7 and 8, or in Figs. 10 and 11, to provide a potted assembly as illustrated at 43 in Figs. 32 and 33.

We have shown in Figs. 35-38 a further modified form of our invention wherein a meter 34 has attached to the rear thereof the illuminating device 60. The illuminating device 60 comprises a molding housing having a cavity 61 therein for vertically mounting the incandescent lamp 62 in a position in which the lamp transmits light rays through the space 63 which is directly aligned with the rear of the scale of the meter for illuminating the scale. Electrical connections are made to the lamp 62 through terminals indicated at 64.

The illuminating device 60 is peripherally aligned with the contour of meter 34 and is somewhat greater in contour than a semi-cylindrical section throughout one part of its contour as represented more clearly in Figs. 35, 39 and 40. The potted assembly containing the electrical circuit components which connect with the terminals of the electric meter is represented at 65, containing, for example, the electrical resistors 66, 67 and 68 embedded therein. The panel on which the potted assembly is formed is represented at 69 through which the fastening screws 70 and 71 extend. The fastening screws 70 and 71 are internally screw-threaded at the ends thereof represented at 70a for example. and engage over the screwthreaded ends of the terminal screw of the electric meter.

The fastening means 70 and 71 terminate at the rear of the potted assembly at 7011 and 71b and are provided with connecting lugs 70c and 71c as shown more clearly in Figs. 37 and 38. The terminal posts 72 embedded in the potted assembly 65 serve to establish electrical connection with the electrical components within the molded mass 65.

The structure of our invention is particularly suitable for miniature electric meters having diameters of the order of one inch and operative with a scale of The illuminating device is particularly applicable to miniature meters of one and one-half inch and facilitates the mounting of such small meters in close compact relation with respect to associated equipment on an instrument panel. The potted assembly of our invention is particularly applicable for association with electrical apparatus generally where contours are matched to con serve space.

The potted assembly in its various forms has been found to facilitate mass production at a rapid rate and at relatively low cost and while we have illustrated the potted assembly as applied particularly to an electric meter, we desire that it be understood that such potted assemblies are also applicable to devices and apparatus other than electric meters and that no limitations upon our invention are intended other than may be imposed by the scope of the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A potted assembly for electrical apparatus comprising in combination with the terminal connectors of an electrical apparatus, a plate of insulation material, terminal. connectors carried by said plate and projecting on opposite sides thereof, electrical components supported by said connectors on one side of said plate, and a mass of insulation material united with one side of said plate and embedding said electrical components and aligned at its sides to conform with the peripheral edges of said plate, the opposite side of said plate forming an exposed confining end for said electrical apparatus and in which said electrical apparatus consists of a cylindrical meter and wherein said plate of insulation material has a con tour conforming with the periphery of said meter and wherein said mass of insulation material forms a cylindrical protective coating around said electrical compo nents and conforms with the contour of the periphery of said plate and said meter.

2. A potted assembly for electrical apparatus comprising in combination with the terminal connectors of an. electrical apparatus, a plate of insulation material, terminal connectors carried by said plate and projecting on opposite sides thereof, electrical components supported by said connectors on one side of said plate, and a mass of insulation material united with one side of said plate and embedding said electrical components and aligned at its sides to conform with the peripheral edges of said plate, the opposite side of said plate forming an exposed confining end for said electrical apparatus and in which said electrical apparatus consists of an electric meter and wherein said plate of insulation material conforms with the peripheral contour of the rear of said meter and wherein said mass of insulation material projects forwardly from said plate toward said meter and elongated members forming electrical circuit connections extending through said mass of insulation material and establishing connection with the terminal connectors for said electrical components on said plate.

3. A potted assembly for electrical apparatus comprising in combination with the terminal connectors of an electrical apparatus, a plate of insulation material, terminal connectors carried by said plate and projecting on opposite sides thereof, electrical components supported by said connectors on one side of said plate, and a mass of insulation material united with one side of said plate and embedding said electrical components and aligned at its sides to conform with the peripheral edges of said plate, the opposite side of said plate forming an exposed confining end for said electrical apparatus and wherein said electrical apparatus consists of an electric meter of substantially cylindrical contour and wherein said plate and mass of insulation material has a substantially semi-cylindrical transverse contour and is disposed immediately adjacent the rear of said meter with the semicylindrical contour thereof substantially aligned with the substantially cylindrical contour of said meter.

4. An electric meter assembly comprising an indi cator unit having a calibrated indicating scale associated therewith, screw threaded connectors extending rearwardly from said unit, a pair of block assemblies of insulation material substantially conforming in peripheral contour with the contour of said unit, one of said block assemblies enclosing a light source focussed upon said cali- *brated indicating scale in said unit and the other of said block assemblies enclosing electrical circuit components, said screw threaded connectors operating to mount said block assemblies with respect to said unit and establish electrical connection with the electrical circuit components in said last mentioned block assembly, said screw threaded connectors extending on opposite sides of the,

light source in said first mentioned block assembly.

5. An electrical meter assembly comprising an electric meter unit having a calibrated indicating scale thereon and terminating in screw threaded members extending from the rear thereof, a pair of block assemblies of insulation material coacting to substantially conform in peripheral contour with the contour of said meter unit, one of said block assemblies being supported on said meter unit by said screw threaded members, a light source mounted in said block assembly, means for directing light rays from said light source upon said calibrated indicating scale in said meter, the other of said block assemblies containing electrical circuit components, and means electrically connecting the said components with said electric meter, where said last mentioned block assembly is disposed immediately beneath said first mentioned block assembly and conforms in contour with the rear of said electric meter.

References Cited in the file of this patent UNITED STATES PATENTS 1 ,660,285

Weston Feb. 21, 1928 2,150,836 Lamb Mar. 14, 1939 2,391,038 Rifenbergh Dec. 18, 1945 2,511,436 Kauth June 13, 1950 2,576,583 Emery Nov. 27, 1951 2,613,252 Heibel Oct. 7, 1952 OTHER REFERENCES 

